Frost flowers is the name commonly given to a condition in which thin layers of
iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
are extruded from long-stemmed
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s in autumn or early winter. The thin layers of ice are often formed into exquisite patterns that curl into "petals" that resemble flowers.
The formation of frost flowers, also known as "ice flowers," is apparently dependent on a
freezingIn physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is almost the exact opposite of freezing...
weather condition occurring when the ground is not already frozen.
Frost flowers is the name commonly given to a condition in which thin layers of
iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
are extruded from long-stemmed
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s in autumn or early winter. The thin layers of ice are often formed into exquisite patterns that curl into "petals" that resemble flowers.
Formation
The formation of frost flowers, also known as "ice flowers," is apparently dependent on a
freezingIn physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The freezing point is the temperature at which this happens. Melting, the process of turning a solid to a liquid, is almost the exact opposite of freezing...
weather condition occurring when the ground is not already frozen. The
sap in the stemSap is a fluid transported in xylem cells or phloem sieve tube elements of a plant. Fluid found in the vacuoles of other cells is sometimes referred to as "cell sap"...
of the plants will expand (water expands when frozen), causing long, thin cracks to form along the length of the stem. Water is then drawn through these cracks via
capillary actionCapillary action, capillarity, capillary motion, or wicking refers to two phenomena:1 The movement of liquids in thin tubes.
2 The flow of liquids through porous media, such as the flow of water through soil....
and freezes upon contact with the air. As more water is drawn through the cracks it pushes the thin ice layers further from the stem, causing a thin "petal" to form. In the case of woody plants and (living or dead) tree branches the freezing water is squeezed through the pores of the plant forming long thin strings of ice that look uncannily like hair i.e. "frost beard".
The petals of frost flowers are very delicate and will break when touched. They usually melt or
sublimateSublimation of an element or compound is a transition from the solid to gas phase with no intermediate liquid stage. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below the triple point ....
when exposed to sunlight and are usually visible in the early morning or in shaded areas.
Examples of plants that often form frost flowers are white
crownbeardCrownbeard is the common name of Verbesina, a genus of flowering plants, in the daisy family . They bear yellow flowers similar to small sunflowers. The name Verbesina refers to the similarity of the foliage to that of the verbena.Verbesina species are used as food plants by the larvae of some...
(
Verbesina virginica), commonly called frostweed, yellow ironweed (
Verbesina alternifolia), and
Helianthemum canadense. The have also have been observed growing from fallen branches of conifers and contain enough hydraulic power to strip the bark off.
Names
Frost flower formations are also referred to as "ice flowers", "ice blossoms", "frost castles", "frost beard", "ice castles", or "ice ribbons".
A related
phenomenonA phenomenon is any observable occurrence. In popular usage, a phenomenon often refers to an extraordinary event. In scientific usage, a phenomenon is any event that is observable, however commonplace it might be, even if it requires the use of instrumentation to observe it...
is
needle iceNeedle ice is a phenomenon that occurs when the temperature of the soil is above 0°C and the surface temperature of the air is below 0°C. The subterranean moisture is brought to the surface via capillary action....
that is extruded from soil.
The name "frost flowers" is also a name given to formations on newly formed ice in the
arcticThe Arctic is the region around the Earth's North Pole, opposite the Antarctic region around the South Pole. The Arctic includes the Arctic Ocean and parts of Canada, Greenland , Russia, the United States , Iceland, Norway, Sweden and Finland.The word Arctic comes from the Greek αρκτικός , "near...
, or, in colloquial language, to some ice crystals.
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